Connect a computer to the Alcatel Modem and enter 10.0.0.138 and see if you can get the Web interface. The modem seems similar to the Alcatel 510. If it is it supports PPOe and PPoA and bridge mode, has a DHCP server and supports NAT. If you can get into the web interface, you can determine how you are connecting. If iti s using PPOE, you may be able to disable the DHCP server and set in in bridged mode and use your WRT54G to connect. DHCP and DNS do not usual pass through NAT.